1. Field of the Invention
The present invention relates generally to municipal solid waste disposal, reclamation and recycling. Municipal solid waste (hereinafter “solid waste”) disposal can be generally defined as the disposal of normally solid or semi-solid materials resulting from human and animal activities that are useless or unwanted, and not hazardous or toxic.
Solid wastes may be further classified in two groups as follows: “garbage” which is decomposable wastes from food, and “rubbish” which is either combustible wastes (such as paper, wood, and cloth) or non-combustible wastes (such as metal, glass, plastics and ceramics).
The present invention is primarily directed to a system and apparatus for reducing and converting (hereinafter “processing”) of solid waste comprised of garbage and rubbish produced in the home (hereinafter “Municipal Solid Waste” or “MSW”) and the equipment for carrying out such processing into a reusable end product or article.
2. Description of the Related Art
Historically, a municipality's chosen method of disposing of its municipal solid waste depended almost entirely on costs, and more recently environmental conditions, both of which are likely to reflect the local circumstances. Composting of solid wastes accounts for only an insignificant fraction of the solid waste stream.
By far the most common method of solid waste disposal in the United States is the deposition of such wastes on land or in “landfills”. Landfills are believed to account for more than ninety percent of the nation's municipal refuse and incineration accounts for most of the remainder. Until now, a sanitary landfill was considered the cheapest most satisfactory means of disposal by most municipalities, but only if suitable land is within an “economic range” of the source of the wastes (i.e., geographic proximity making waste removal and hauling economically feasible). Collection and transportation costs are known to account for seventy-five percent of the total cost of solid waste disposal and management.
In modern landfills the refuse is spread in thin layers, each of which is compacted by heavy industrial equipment before the next layer is spread. When about ten feet of refuse has been deposited, it is covered by a thin layer of clean earth which also is compacted. Pollution of surface and groundwater is believed to be minimized by lining and contouring the fill, compacting and planting the cover, selecting proper soil, diverting upland drainage, and placing wastes in sites not subject to flooding or high groundwater levels. Landfills are known to generate flammable gases through the anaerobic decomposition of the organic solid waste and thus proper venting and burning of the gases, usually methane, is often necessary to eliminate or alleviate potentially dangerous conditions.
The second most popular method of solid waste disposal is incineration. Incinerators of conventional design burn refuse on moving grates in refractory-lined chambers. The combustible gases and the solids they carry are burned in secondary chambers. Combustion is eighty-five to ninety percent complete for the combustible materials. In addition to heat, the products of incineration include the normal primary products of combustion including carbon dioxide and water, as well as oxides of sulfur and nitrogen and other gaseous pollutants. The nongaseous products are fly ash and unburned solid residue. Emissions of fly ash and other particles are often controlled by wet scrubbers, electrostatic precipitators, and bag filters positioned inside or adjacent the exhaust stacks.
On the downside, landfill and incineration methods of disposal have been known to pose significant environmental problems and the associated health concerns by the municipalities, government, private industry, and individuals are increasing. Therefore, a growing trend associated with the treatment and handling of solid waste material is “resource recovery”. Resource recovery is intended to recover useful materials from raw municipal solid waste and the handling may include grinding or shredding machines, magnetic separators, air classification that separates the light and heavy fractions, screening, and/or washing. Resource recovery methods, therefore, attempt to reduce (i.e., recycle) the solid waste into a more manageable, although not always useful, form, but such methods are quite costly.
In all known methods of solid waste disposal (e.g., reduction, treatment or resource recovery), the resultant end product may further include microbes or microorganisms that require careful consideration and handling prior to disposal. In such cases the by-products are believed to remain waste materials not suitable for use or transformation into useful articles.
The present invention relates generally to municipal solid waste handling and disposal, but is actually believed to be the most desirable solution to the growing waste problem because the cost effective and resource recovery methods used, as well as the physical characteristics of the processed material end product.
The art to which the invention relates includes and is believed to be limited to the information of the type disclosed in U.S. Pat. No. 6,017,475 granted to Cantrell which is incorporated by reference as if fully set forth herein. The '475 patent is directed to a process of transforming household garbage into useful materials.